1. Field
The present disclosure relates to semiconductor devices and/or methods of manufacturing the same, in more particular, to high electron mobility transistors (HEMTs) and/or methods of manufacturing the HEMTs.
2. Description of the Related Art
Various power conversion systems include a device for controlling flow of an electric current through ON/OFF switching operations, that is, a power device. In a power conversion system, efficiency of the entire system may be depend upon efficiency of a power device.
Power devices that are currently commercialized are mostly power metal-oxide-semiconductor field-effect transistors (MOSFETs) or insulated gate bipolar transistors (IGBTs) which are based on silicon (Si). However, it is difficult to increase efficiency of the power device based on the silicon due to limitations in physical properties of the silicon and in manufacturing processes. Accordingly, research for increasing conversion efficiency by applying group III-V based compound semiconductor to a power device is being conducted. In this regard, high electron mobility transistors (HEMTs) using a heterojunction structure of compound semiconductors have drawn attention.
HEMTs may include semiconductors having different electric polarization characteristics. In a HEMTa HEMT, a semiconductor layer having relatively large polarizability may induce a 2-dimensional electron gas (2DEG) in another semiconductor layer adhered to the semiconductor layer. Electronic mobility in the 2DEG may be very high. However, in order to efficiently use a HEMTa HEMT in various electronic devices, it is desired to improve or adjust the characteristics of the HEMT. In particular, it is desired to improve or adjust an on-current level, a threshold voltage, and the like of the HEMT.